Lithography mask for imaging of convex structures
a technology of convex structure and lithography mask, which is applied in the field of lithography mask, can solve the problems of unstable behavior of bend locations of convex structures and unstable behavior of convex structures not only in the case of alternating phases
Inactive Publication Date: 2005-05-05
POLARIS INNOVATIONS LTD
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Benefits of technology
[0019] Consequently, the preferred embodiment of the present invention provides a lithography mask which, even when defocusing of the exposure radiation occurs, reduces constructive interferences in the convex bend region in such a way that the quality of the exposed convex structures, in particular the convex bend regions thereof, is improved.
Problems solved by technology
Particularly in the case of phase masks as lithography masks for circuits having a high integration density, the bend locations of convex structures have an unstable behavior with regard to a defocusing of the exposure system used.
However, the unstable behavior at convex structures occurs not only in the case of alternating phase masks but also in the case of conventional lithography masks without phase-shifting regions.
In the concave bend region, the rounding is due to the fact that the intensity of the exposure radiation in this region, on account of the small dimensions of the bend region in comparison with the wavelength of the exposure radiation, does not suffice to ensure an exposure right into the rectangular concave corner region.
This effect is referred to as unstable behavior of the convex structure with regard to the defocusing and is a consequence of severe constructive interferences.
Method used
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Embodiment Construction
[0086] The figures uniformly show alternating bright-field phase masks as lithography masks. However, the second and third variants according to the invention can generally be applied to lithography masks while the first variant can generally be applied to alternating phase masks.
[0087] The angled structure element O of the embodiment of the first phase mask variant according to the invention as illustrated in FIG. 2a corresponds in terms of its construction and its dimensions to the angled structure element O from FIG. 1a. Therefore, reference is made to the explanations already made with regard to the prior art.
[0088] In contrast to the phase mask structures that are known from the prior art and illustrated in FIGS. 1a and 1b, the angled structure element in FIG. 2a does not have in its convex section A facing the reflex angle α, a continuous transparent segment having the angled construction of the structure element O. A first transparent segment T1 extends along the edge of th...
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Abstract
A lithography mask has an angled structure element (O) formed by a first opaque segment (O1) and by a second opaque segment (O2). The structure element has at least one reflex angle (α). The angled structure element (O) includes at least one convex section (A) facing the reflex angle (α). At least one transparent structure (T) adjacent to the angled structure element (O) is provided at the convex section (A) of the angled structure element (O). The transparent structure (T) is formed in separated fashion at the convex section (A) of the angled structure element (O) and thus comprises two distinguishable transparent segments (T1, T2) formed at least in sections essentially axially symmetrically with respect to the angle bisector (WH) of the reflex angle.
Description
[0001] This application claims priority to German Patent Application 103 40 611.5, which was filed Aug. 29, 2003, and is incorporated herein by reference. TECHNICAL FIELD [0002] The invention relates to a lithography mask for fabricating integrated semiconductor circuits such as VLSI and ULSI circuits by means of photolithography methods. BACKGROUND [0003] Particularly in the case of phase masks as lithography masks for circuits having a high integration density, the bend locations of convex structures have an unstable behavior with regard to a defocusing of the exposure system used. A convex structure is understood to be an angled structure element formed by a first and a second segment opaque to the exposure radiation where the structure element has a reflex angle. The region facing the reflex angle is referred to as convex section with the convex bend location, and the region facing away from the reflex angle is referred to as concave section of the angled structure element. [000...
Claims
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IPC IPC(8): G03C5/00G03F1/00G03F7/20G03F9/00
CPCG03F1/144G03F7/70466G03F7/70441G03F1/36G03F1/30
InventorMOUKARA, MOLELALUDWIG, BURKHARDTHIELE, JORGAHRENS, MARCOKOHLE, RODERICKPFORR, RAINERMORGANA, NICOLO
OwnerPOLARIS INNOVATIONS LTD